82 



fiith and last row of maize should be planted to trap the eggs of the 

 few remaining moths that have matured, these being destroyed by 

 burning. 



The success of this method depends entirely on the maize being in 

 tassel in December, to ensure which, it must be planted considerably 

 later than the normal time of planting in spring. 



Duncan (R. S.). The Farmer's Apple Orchard. — 38ih Ann. Rept. 

 Ontario Agric. & Experimental Union for 1916, Toronto, 1917, 

 pp. 62-67. [Received 31st December 1917.] 



In the course of this paper the importance of spraying as an invest- 

 ment, and the necessity for proper equipment are emphasised. A 

 summary of spraying rules against the commoner insect and fungus 

 pests of apple orchards is given. 



Jones (T. H.). The Sweet-Potato Leaf-Folder.— C7. S. DejJt. Agric, 

 Washington, D.C., Bull. no. 609, 22nd November 1917, 12 pp., 

 4 figs. 



The only recorded damage to sweet potato by the larva of the Pyralid 

 moth, Pilocrocis tripuncfata, F. {cubanaUs, Guen.), is that reported 

 in 1915 from Porto Rico, though this species is known to occur 

 in Texas, Mexico, Costa Rica, Jamaica, Cuba and Grenada. 



The eggs are laid singly or in small irregular groups on the under- 

 surface of the leaf, frequently alongside the leaf-veins. They hatch in 

 four days, and the larvae undergo six moults in 13 days, after which 

 they construct cocoons within which they pass the prepupal period of 

 2 days in the case of the summer generations (the last geueration, 

 however, hibernating in the last larval instar) ; a pupal stage of 6 

 days completes the 25 day life-cycle. 



This pest, which has five generations in the year, and which damages 

 the plant by practically skeletonising the leaves, can be successfully 

 controlled by spraying with a solution of zinc arsenite powder, 1 lb. in 

 40 U.S. gals, water in which 12 lb. cactus detritus has been soaked for 

 20 hours previously to increase the adhesiveness, or with a solution of 

 1 lb. lead arsenate powder in 50 U.S. gals, water, one early application 

 being sufficient. 



Two parasites have been reared from the larvae, a Tachinid, 

 Exorista pyste, Wlk., and an Ichneumonid, a new species of Bassus, 

 while the larvae are attacked by the adults of Podisus maculivenlris. 

 Say (spined soldier-bug). The jackdaw or boat-tailed grackle, 

 Megaquiscahs major macronrus, is predaceous on the larva. 



DE Ong (E. R.). Hydrocyanic-acid Gas as a Soil Fumigant.— JL Agric, 

 Research, Washington, D.C., xi, no. 9, 26th November 1917, 

 pp. 421-436, 1 plate, 10 tables. 



The study of the use of hydrocyanic acid, the most effective 

 substance known as a soil fumigant in orchards and greenhouses, 

 entails the establishment of a definite ratio between the minimum 

 point of toxicity to insects and the maximum dosage that is safe for 

 germinating seeds and plants, together with a knowledge of the 

 physical and chemical action of the gas in the soil, the rate and extent 



